Update for anyone that cares.
The insurer listened to the original sales call. As I was in work at the time they left a message stating that I told them I passed my test a month prior to taking out the policy, yet I wasn't asked for a specific date so they said I was liable to pay the additional premium. So I called back and literally spent half an hour trying to get through to some idiot in customer services who was thick as two short planks. He finally accepted it was their fault and said he would speak to the sales guys to sort the policy out. I'm not an aggressive person and I try to remain well mannered on the phone as I understand the mistake wasn't exactly the fault of the person I was speaking to at that moment in time but I expect them to understand basic mistakes made by their sales team.
Anyway I got a call back from some guy in sales saying sorry for the balls up and that they would cancel the policy and re-start it due to the costs they would incur from the underwriters. I thought 'fair enough', he explained no additional premium would be taken, we confirmed the two pieces of data they consistently got wrong, the registration of my bike and the date I passed my test. I hung up the phone feeling quite glad I'd finally got the situation sorted.
Today the new policy documents hit my doorstep and low and behold we have a different policy premium, nearly £100 more, a different registration and another made up date of when I passed my motorbike test. I couldn't quite believe my eyes. The funniest part (if you can call it that) is that they have copies of my driving licence so they can reference the dates, they corrected my registration on the previous documents and I haven't supplied any further card details for the payment they propose to take and if they do take it I will swiftly lose the good manners I have kept throughout this situation.
I called their customer service department to find out about the errors on my policy and the woman on the phone couldn't have cared less, she took the correct details and offered no answers about the new premium. Checked my bank to see if anything extra had been taken - it hadn't. So I called back, hoping to get through to someone else, and I got through to the same woman who quickly dismissed me when she realised she had spoken to me 10 minutes earlier. Disgusting insurance company.
Prior to taking out the insurance I wish I had read the reviews of this company on moneysupermarket. I would strongly advise anyone who gets the best quote from them to go for the next cheapest quote and not give this company your business.